The Dow industrials lost more than 1,300 points, or 6.3%. After a brutal few weeks, the Dow has now lost nearly all of its gains since President Trump's inauguration.
The sharp losses triggered another temporary trading halt in the afternoon. Even prices for investments seen as very safe, like longer-term U.S. Treasurys, fell as investors rushed to raise cash.
The S&P 500 index fell 131.09 points, or 5.2%, to 2,398.10.
The Dow Jones Industrial Average fell 1,338.46 points, or 6.3%, to 19,898.92.
The Nasdaq fell 344.94 points, or 4.7%, to 6,989.84.
The Russell 2000 index of smaller company stocks fell 115.34 points, or 10.4%, to 991.16.
For the week:
The S&P 500 is down 312.92 points, or 11.5%.
The Dow is down 3,286.70 points, or 14.2%.
The Nasdaq is down 885.03 points, or 11.2%.
The Russell 2000 is down 218.97 points, or 18.1%.
For the year:
The S&P 500 is down 832.68 points, or 25.8%.
The Dow is down 8,639.52 points, or 30.3%.
The Nasdaq is down 1,982.76 points, or 22.1%.
The Russell 2000 is down 677.30 points, or 40.6%.